The invention concerns a dialysis membrane from cellulose regenerated from cuoxam solution, i.e. an ammoniacal solution of cupric hydroxide which dissolves cellulose in the form of a hollow fiber with a continuous hollow interior.
From DE-PS No. 736 321 are known hollow fibers from regenerated cellulose which is regenerated from cuoxam solution, with continuous hollow interiors.
The U.S. Pat. No. 3,228,877 teaches that hollow fibers prepared as described in DE-PS 736 321 can be used as dialysis membranes and as membranes for reverse osmosis.
From US-PS No. 3,888,771 are known hollow fibers from cellulose regenerated from cuoxam solutions which exhibit a defined membrane structure and which along the total axis of the fiber have uniform wall thickness and a true circular cross-section. In addition, the hollow fibers are highly stretched and exhibit high tensile strength. With this type of high stretching of cellulose regenerated from cuoxam solutions, one observes a double refraction .DELTA.n of 0.03. Although the high strength which can be obtained through stretching of the fibers is desirable, it is of great disadvantage to the swelling ability of the membrane and thereby for the effectiveness in dialysis.
In dialysis, for example in hemodialysis, it is advantageous that the dialysis membranes, in the form of hollow fibers, are associated into bundles. The fine hollow fibers form bundles, in which the hollow fibers can lie very close together quite easily, and they have a tendency at fiber densities of between about 500 to 1000 fibers/cm.sup.2 to associate very tightly along their entire lengths, in a manner analogous to the glass plate effect between two flat parallel plates.
Through this association, the introduction of dialysate liquids into the intermediate spaces between the hollow fibers is made much more difficult, and the surfaces at which the fibers lie closely against one another are not used in the exchange process, through which the effectiveness of the hollow fiber modules in greatly reduced.